Update plot_pdb.py

plot_pdb.py

@@ -6,7 +6,7 @@ def display_pdb_by_pdb(pdb):
     # function to display pdb in py3dmol
     # ref: https://huggingface.co/spaces/AIGE/A_B
 
-    view = py3Dmol.view(width=500, height=500)
+    view = py3Dmol.view(width=500, height=500, background=black)
     view.addModel(pdb, "pdb")
     view.setStyle({'cartoon': {'color': 'spectrum'}})
     view.zoomTo()